My present invention relates to a reflector-type lighting fixture for in the wall, in the floor or in the ceiling mounting and in which a parabolic reflector has, substantially at its focal point, a light source.
A reflector-type lighting fixture for the purposes described has been discussed in principle in the Handbook for Lighting, xe2x80x9cHandbuch fur Beleuchtungxe2x80x9d, 4th Edition, Verlag W. Girardet, Essen, page 107, 1975. In such fixtures, the light emerges from the open side and the reflector features refraction from the parabolic surface and derives from a lamp located generally at the focus of the parabola.
When parabolic reflector fixtures are used as in the floor lamps, the parabolic reflector is generally very flat and one of the characteristics of prior art reflector fixtures of this type is that the light can be blinding to an observer. The blinding effect of the light can be avoided by shielding the light source in a cup so that a direct line of sight between a person and the light source cannot occur.
A cone-type reflector for similar applications, i.e. adapted to be built into the floor, wall or ceiling can be found in the ERCO lighting program brochure (ERCO Leuchtenprogramm) published 1993/95, page 55. Here the reflector, a conical reflector which can have a socket or the like receiving the lamp itself and connected to a mounting, allows all purpose use of the lamp. This system permits a variation, by axial shifting of the reflector relative to the lamp, to vary the spreading of the illumination field.
Notwithstanding the fact that such lamps are widely used, it is still desirable to provide an in-the-wall, in-the-floor or in-the-ceiling reflector lamp which has a compact construction and can provide a blinding-free illumination.
It is, therefore, the principal object of the present invention to provide an improved lighting fixture which extends the principles of the prior art lighting fixtures described previously and is nevertheless more compact and generally flatter and capable of providing blinding-free illumination.
Another object of the invention is to provide a lighting fixture which can be more effectively used for in-the-floor, in-the-wall and in-the-ceiling illumination than fixtures known heretofore and which in spite of their flat and compact construction are free from the drawbacks previously mentioned of earlier fixtures of that type, i.e. free from the tendency to blinding the user or viewer.
These objects and others which will become apparent hereinafter are attained, in accordance with the invention in a lighting fixture of the type which comprises a parabolic reflector having an apex and a focus and wherein the parabolic reflector is effectively light transmissive only between the apex and a plane perpendicular to the axis of the parabola connecting the apex and the focus and extending through the focus of the parabola.
According to the invention, moreover, the light source is mounted so that it is shiftable in translation relative to the focus and, more specifically in that plane, or is positioned in a relatively shifted location in translation from the focus or at an offset from the focus. That plane, where it intersects the parabola of the reflector can define a circle and the area within that circle can, in turn, be defined as the lumen of the fixture. The reflected light can therefore emerge from the reflector through this lumen, having reflected only from the portion of the reflector between this circle and the apex.
The invention permits a very shallow parabola to be used, i.e. permits the parabolic reflector to be axially shortened by comparison with earlier systems since the parabola needs only extend between its apex and the aforementioned plane so that it, in its axial depth, only corresponds to the spacing between the focus and the apex. The parabola can have an axis of symmetry which is perpendicular to the lumen plane as previously defined and can correspond to the parabola axis mentioned previously.
The parabolic reflector itself can be shortened to terminate at that plane or any part of the reflector structure extending beyond that plane away from the apex can be utilized for other purposes than light delivery, i.e. for mounting the fixture or the reflector or for receiving additional lenses, light-configuring structures, filters or the like, or for mounting the latter in the floor, wall or ceiling. At the light delivery side of the fixture, a window can be provided which can also be mounted on a portion of the reflector beyond the aforementioned lumen plane.
The parabolic reflector of the invention will naturally have a narrower field through which the light emerges than a parabolic reflector which has not been similarly axially shortened but can have a correspondingly greater light flux density across the lumen.
Because the light source is shiftable in translation in the aforementioned plane, the invention affords the possibility of so deflecting the parallel light rays emerging from the fixture that they need not be parallel to the axis of symmetry but rather can emerge at an angle of inclination to the symmetry axis of the parabolic reflector.
In the case of in the floor reflector light fixtures, therefore, it is possible simply by translating the position of the lamp in the aforementioned plane to avoid the blinding phenomenon by causing the light rays to emerge angled toward a wall which can be, for example, at a right angle to the floor and the aforementioned lumen plane.
The same principle can apply to in the wall reflector lighting or reflector lighting which is located above the region to be illuminated and indeed whenever planar surfaces, for example roadways, street areas, entry ways or the like are to be illuminated in a manner free from blinding. It is for example possible to provide reflector lighting according to the invention in entry ways of garages or other traveled ways, especially as in the wall lighting, in which the light outlet plane is vertical and can be located substantially at the level of the lights of the vehicle and thereby to so illuminate the traveled way that the driver is not blinded even when the lamps are directly within the view of the driver.
In any case, direct blinding by the light source of the light fixtures of the invention can be avoided by ensuring that the light emitted by the light source is only delivered by the reflector between the apex and the aforementioned ring and only within the lumen plane. According to a further feature of the invention, the light source can be releasably arrested in any optional position within its translation only. In that case, a multiplicity of in the floor reflector fixtures can be used for uniform wall lighting in spite of significant deviations in the tolerances with which the fixtures are located in the floor. In that case the individual adjustment of the reflector fixtures allows the light to be distributed uniformly along the wall.
According to another feature of the invention, the light source is adjustable along a street light which can be horizontal or vertical and can be perpendicular, where appropriate, to the wall surface to be illuminated. A shifting of the light source away from the wall surface to be illuminated ensures a greater inclination of the light to the wall surface. Naturally, a shift of the lamp in the direction of the wall surface to be illuminated reduces the inclination of the light rays directed at the wall surface.
In order to ensure that the light rays will only emerge between the intersection of the lumen plane and the reflector on the one hand and the apex of the reflector on the other, the light source on its side turned away from the reflector can be covered by an opaque coating or cover (shield). The shield can be curved and can be hemispherical or semicylindrical, depending upon the shape of the light source.
To avoid undesired light reflection, it has been found to be advantageous to locate the free edges of the shield substantially in the lumen plane.
To avoid multiple reflections and thermal effects, the inner surface of the shielding turned toward the light source is preferably of a matte finish or has blackened and most advantageously has a blackened matte finish.
It has been found to be advantageous, especially in the context of the use of the opaque shield of the present invention to employ a light source which radiates in substantially all directions. Preferred light sources are low voltage halogen lamps, for example type QT 12 halogen lamps or halogen metal vapor systematic lamps of the type HIT-CRI 35 with such light sources which can be either circularly cylindrical or generally spherical, the light source can have a lamp bulb which has a cylinder axis substantially in the lumen plane while the opaque shielding at least indirectly is laterally mounted on the reflector and engages partly around the lamp.
The opaque shielding can be at least indirectly secured at one end or at both ends to the reflector. To avoid light losses, it has been found to be advantageous to mount the opaque shielding at least indirectly at only one end laterally on the reflector. The light source can be shifted with its shielding or mounting bracket or relative to its shielding and/or mounting bracket. In the latter case the shielding should be sufficiently large, e.g. larger than the light source, to allow shifting. This ensures that direct blinding cannot occur during the shifting of the light source.
According to a further feature of the invention, a light source can be used which does not have a separate opaque shielding, but rather is so constructed that it is light emissive only on one side. Such light sources are for example LEDs. In that case another feature of the invention is that the light source consists of at least one light-emitting diode.
One side emitting LEDs, whose emissions are directed to the interior of the reflector, require no special opaque shielding.
In the case in which the light emitting diode is of spherical configuration, e.g. hemispherical, the light source may be provided with a separate opaque shielding.
So that there is sufficient light power, the system of the invention can provide that a multiplicity of light emitting diodes can be provided in a tightly packed relationship or along straight lines or curves.
For the displacement of the light source according to the invention, the entire assembly of light emitting diodes can be moved as has been described or the particular point which the light is emitted can be moved by turning on and off one or more light emitting diodes arranged along a straight line or curve.